It has long been established that distinct differences in the metabolic phenotype of cancer cells are linked to underlying mechanisms that provide a selective advantage for survival and proliferation. However, the precise mechanisms that trigger tumorgenesis are poorly understood. It has been postulated that glycolytic adaptation is a survival mechanism that allow tumors to proliferate in a microenvironment characterized by low pH and oxygen tension. These adaptations of “the Warburg shift” provide a selective advantage to the tumor through increased glucose uptake and ATP synthesis in order to meet the demands for biosynthesis, energy and reducing equivalents.
Recent advances in the development of instruments that measure the flux of key analytes indicating aerobic metabolism (O2), glycolysis (H+), and intermediary metabolism (CO2) within the microenvironment may provide insight to the underlying mechanism of malignant transformation. However, these systems are designed and optimized for use in cell-based assays, may lack environmental control, and generally do not facilitate the measurement of multicellular tissue samples because of constraints on chamber size, difficulty in immobilization and perfusion of the sample.
Seahorse Bioscience, Billerica, Mass., launched the XF96 “Extracellular Flux Analyzer” in 2007. Since that time the product has been adopted as a technology platform for making quantitative measurements of mitochondrial function and cellular bioenergetics. XF measurements are performed in a fully integrated instrument that measures the concentrations of various analytes (O2, H+, CO2) in the extracellular media of a cell based assay. Analyte concentrations are measured non-invasively, within a small volume about the cells, providing quantitative measurements for changes in analyte concentrations as a function of time from which bioenergetic flux (example: dO2/dt=oxygen consumption rate, dpH/dt=extracellular acidification rate) can be determined. XF measurements are based on a method in which a small, temporary, measurement volume is created around the cells, or a sensor is placed in close proximity to the cells. Measurements under these conditions amplifies changes in concentrations allowing highly sensitive, time resolved measurements to be collected from a set of optical sensors. Once the measurement is made, the plunger (probe) is lifted and the medium around the cells is restored to its original condition. This nondestructive method allows multiple measurements to be serially collected for a biological sample under various conditions of stimulation (basal, environmental change, compound stimulus).
By measuring key metabolic parameters such as oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), a profile of the bioenergetic phenotype may be developed based on the substrate and pathway (glycolysis or oxidative phosphorylation) for generating energy and biosynthesis. The product allows quantitative measurements of mitochondrial function and cellular bio-energetics of cells.
A need exists for a system that allows for measurement of key analytes of, for example, aerobic metabolism, glycolysis and intermediary metabolism in multicellular tissue.